Joint Participant and Learning Topology Selection for Federated Learning in Edge Clouds

Deploying federated learning (FL) in edge clouds poses challenges, especially when multiple models are concurrently trained in resource-constrained edge environments. Existing research on federated edge learning has predominantly focused on client selection for training a single FL model, typically with a fixed learning topology. Preliminary experiments indicate that FL models with adaptable topologies exhibit lower learning costs compared to those with fixed topologies. This paper delves into the intricacies of jointly selecting participants and learning topologies for multiple FL models simultaneously trained in the edge cloud. The problem is formulated as an integer non-linear programming problem, aiming to minimize total learning costs associated with all FL models while adhering to edge resource constraints. To tackle this challenging optimization problem, we introduce a two-stage algorithm that decouples the original problem into two sub-problems and iteratively addresses them separately with efficient heuristics. Our method enhances resource competition and load balancing in edge clouds by allowing FL models to choose participants and learning topologies independently. Extensive experiments conducted with real-world networks and FL datasets affirm the better performance of our algorithm, demonstrating lower average total costs with up to 33.5% and 39.6% compared to previous methods designed for multi-model FL.